How much water should be left in the Mash Tun?

[St. Jon's Wort]

I just got finished assembling my MLT and I tested it out by filling it halway (about 6 gallons) with hot water. I checked it for leaks first, and there were none. I then proceeded to drain it out to check the flow rate and the action. It drained very well at first but stopped draining with about 3/8 of an inch of water left in the bottom (about 3/4 of the height of my 1/2" diamter copper tubing). Is this normal or did I do something wrong?

 

[JKoravos]

as soon as it starts sucking air it will stop flowing. Don't worry about it. 3/8" of liquid is nothing.

If you're pre-calculating your required water, just measure the volume that's left in there and add it to your system's dead space.

 

[Whiskey]

Depending on what he is using for a MLT 3/8 can be a lot.

You can minimize the dead space adding a pick up tube before the braid/manifold.

 

[St. Jon's Wort]

What do you mean by pick up tube?

I am using a 48 qt. chest cooler. I'm not certain of the inside dimensions but 3/8" in the bottom of it probably equates to a quart of water or so I'd guess.

 

[Whiskey]

Sorry about that, I sent via iPhone so I had to keep it short given my massive thumbs do not work with that stupid little keyboard.

A pick up tube is just a bent piece of copper (SS, pvc whatever) tubing that allows suction to pull most of the flui from below the port in your MLT (Kettle, bucket etc).

I used about a 3" piece of 3/8 tubing that is bent down before it attaches to my braid. I get all but 2 cups out of my MLT. It helps that my cooler is slightly concave so the wort/water pools a bit.

 

[St. Jon's Wort]

I just checked it and I overestmated quite a bit. The amount that is left over accounts for only about 2 cups of water. That is the same amount that you state is left over in yours. So, is that normal? I'd like to do my first all-grain this weekend and I want to make sure that everything is working perfectly.

Also, for anyone who can help - I made my manifold out of 1/2" M copper tubing. Is there any kind of cleansing particular to copper that I need to do? I've noticed a large amount of copper dust that is escaping from the water that I run through my MLT. I want to ensure that it is 100% clear before my first AG batch. If anyone can help me out her ethat would be great.

 

[Gremlyn]

As long as you account for the dead space in your water calculations, it's just fine. Just run a good amount of hot water through the system before using it and it will be good to go.

 

[Clayton]

this is easy to fix!!!

all you have to do is. " this is what i did"

on my ice chest MLT i use a copper pipe manifold
and i used the existing tap hole for my drain.

so on the pipe comeing off the valve heading to the manfold just cut a small hole down in the dip just before it exits the wall of the cooler that is the lowest point in the cooler and if there is a small hole there it will drain the remaning wort. i just use a hack saw the same way i put slits in the manfold i put one in pipe , that hole drains the last bit.

 

[Clayton]

oh also , on my manfold i had tons of copper dust.
i wash and wash it and thought i got it all. i used a bandsaw so i had lots of cuts.

well after my first batch with it when i drump the trub-yeast i saw some copper dust
i saw some in the kettel too.
the beer turned out great no big deal(one of my best steam beers
there is alot of talk about copper posioning but thats not just pure copper, its copper salts, all beer was made in copper kettels in the past,and what copper salts do get in your beer are locked up by the yeast thay will strip it all out, yeast are about 100 times more sinsative to copper posioning that a human , so if the yeast do well you will too

 

[JKoravos]

Don't worry, the copper will settle out before the yeast.

 

[wilserbrewer]

"How much water should be left in the Mash Tun?

Ideally none. But in reality I feel it doesn't make that big a difference. You can just tilt the tun to get the last cup or two of runnings for the first and second sparge. By the last sparge, I feel the runnings are thin enough not to make that much difference.

If you have a gallon of dead space in the bottom of the tun, the amount of runnings retained will be far less due to the displacement of the grain. YMMV